Viewing x different pages with one vertical bar to compare products

I just needed it again - a lot of websites don't support a "compare" feature ... so opening various product pages (normally from one domain) but incl. one vertical bar to scroll up-and-down all websites to compare products.

Some other people requested it in years back but threads are locked now. (e.g. split view).

One vertical scrollbar may be a somewhat different request anyway ... in old (Presto-based) Opera there were two different options referred to as Tiled and Linked, Tiled allowed several pages to be viewed at the same time, but each pane was separate and could be scrolled or navigated independently. Linked was specifically for side-by-side comparisons and scrolled both panes together. You're asking for something more like Linked tabs - some people just want to more efficiently use space on large monitors by showing multiple (potentially unrelated) pages at the same time.